<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        .box{
            height: 200px;
            width: 200px;
            background-color: green;
            /*让 box 盒子消失的方法*/
            /*display: none;*/
          opacity: 0;   /*transition 过度效果*/
            /*visibility: hidden;*/
           /*  position: absolute;
           left: -9999px;
            /*transform: scale(0);缩放*/
        }
        .box:hover{
            opacity: 1;
            transition: opacity 5s;
                    }
     /*   .container{
            height: 0px;
            overflow: hidden;
        }*/
    </style>
</head>
<body>
   <!--  <div class="container"> -->
         <div class="box"></div>
         顶顶顶顶顶顶顶顶顶顶顶顶
    <!-- </div>
    -->
</body>
</html>